Monday, January 30, 2012

Plaesiomys brachiopod from the Verulam fm

Plaesiomys is easily recognized while collecting in the Verulam formation. It has a rectangular outline and strong radiating ribs on the surface of the pedicle and brachial valves. It also has a triangular shaped interarea in the posterior.

Specimen 1 pedicle valve

Specimen 1 anterior

Specimen 1 brachial valve

Specimen 1 posterior

Specimen 1 profile

Specimen 2 pedicle valve

Specimen 2 anterior

Specimen 2 brachial

Specimen 2 posterior

Specimen 2 profile

Both of the above specimens were collected from the Verulam formation which is middle Ordovician in age (Katian/Mohawkian stage) near Brechin, Ontario.

Saturday, January 28, 2012

Partial Ceraurus trilobite from the Verulam fm.

The first Ceraurus I've ever found was from the Verulam formation and is pictured below. It's not complete but it is enrolled. You can see the stubs of one of the spines which extend from the Pygidium curving out.

Here is an angled view that shows the meet point between the Cephalon and Thorax

Based on the images in William Hessin's book "South Central Ontario Fossils", 2009, I am going to go out on a limb and say that this trilobite might be a Ceraurus globulobatus. I can'tr really be sure until I get the cephalon cleaned off a little more.

The specimen was collected from a quarry near Brechin, Ontario, Canada in the Verulam formation which is middle Ordovician in age (Katian/Mohawkian stage).

Thursday, January 26, 2012

Thaleops (or Nanillaenus) trilobite cephalon from the Verulam fm.

Another new trilobite genera for me, from the Verulam formation, is Thaleops. I found two specimens on my last trip up to Canada.

This first specimen is a somewhat complete cephalon

A closer view shows the glabella. the body would have extended back towards the top of the picture.

A view looking at the back of the Cephalon.

The second piece I found was an isolated glabella.

Both specimens were collected from the Verulam formation (although at different levels) which is Ordovician (Katian/Mohawkian stage) in age.

My friend Kevin has a nice specimen, that he found in the same quarry as my specimens above, of what he called Nanillaenus in his gallery on the Fossil Forum.

There is some debate about Thaleops and Nanillaenus and which is a proper name. I found a paper from 2004 published in the "Journal of Systematic Paleontology" that synonimizes Nanillaenus with Thaleops. See the link below:

By Lisa Amati and Stephen R. Westrop (2004) from the Journal of Systematic Palaeontology, Volume 2,
Issue 03, September 2004 pp 207-256

Tuesday, January 24, 2012

Rhyncotrema brachiopod from the Verulam fm

Rhyncotrema is a small Rhynconellid brachiopod that is somewhat common in the Verulam formation. You can usually distinguish it from Lepidocyclus as the pedicle and brachial valves are flat to slightly convex rather than highly convex. This statement is incorrect as I write in this post.

Pedicle valve


Brachial valve



Here is another specimen

Pedicle valve


Brachial valve



Both specimens were collected from the Verulam formation which is Ordovician in age (Katian/Mohawkian stage) near Brechin, Ontario.

Sunday, January 22, 2012

Partial Amphilichas trilobite cephalon from the Verulam fm.

This next specimen was a surprise find for me. I flipped a piece of rock upside down and saw the fossil below lying on the surface. It's the glabella from a cephalon of the trilobite Amphilichas. From talking to my friend Kevin, who regularly collects in the quarry we were in, it's pretty rare to even find this much in the Verulam fm.

It's too bad there wasn't more of the cephalon present but I'm pretty happy with this new genera to add to my collection. Based on the book "South Central Ontario Fossils" by William Hessin, the specimen could be Amphilichas ottawaensis. I found this in the Verulam formation of Ontatio, Canada which is middle Ordovician (Katian/Mohawkian stage) is age.

A slightly more complete cephalon of a Amphilichas can be seen here.

The Dry Dredgers have a page here with several examples of this genera found in the rocks around Cincinnati.

Friday, January 20, 2012

Hemiarges paulianus trilobite cephalon from the Verulam

Hemiarges paulianus is one of the many trilobites found in the Verulam fm of Ontario, Canada. I've only found the cephalon of this species thus far as can be seen below.

I like the bumpy surface on the exterior of the cephalon. I've read where these may have had sensory hairs or other organs to help the animal find it's way. Otherwise I think it is blind as I can't see any eye structures.

My friend Joe has a complete specimen on his website here.

Wednesday, January 18, 2012

Rafinesquina alternata brachiopod from the Verulam fm

One of the common index fossils of the Ordovician is Rafinesquina alternata. This prolific orthid brachiopod is extremely common in the upper Ordovician rocks around Cincinnati and Kentucky but is slightly less common in the middle Ordovician Verulam fm. Another interesting feature is that the size of the shells is smaller than those from around Cincinnati.

Here is a typical specimen that is loose from matrix.

Pedicle valve


Brachial valve



Here is a solitary specimen still in matrix.

This plate of Prasopora bryozoans has a Rafinesquina brachiopod among it

Several specimens on a mixed plate with a Lepidocyclus Rhyncotrema brachiopod and a Prasopora bryozoan among shelly debris.

Monday, January 16, 2012

Escharopora bryozoan from the Verulam fm.

Escharopora is a uncommon bryozoan but I've found many good examples in the Verulam formation in Canada. I've shown a couple of specimens in a prior post but the ones shown below were collected this past fall.

Escharopora tends to form long, thin colonies that are shaped like a sword. This plate of matrix has a very long specimen of Escharopora that is almost 3 inches in length.

The skeleton shows some cracks that likely formed as the sediment was compressed during the dewatering phase.

Here is the growing tip of the colony but the anchor end (a slightly curved point) is missing from the specimen.

Here is a loose specimen that shows the classic sword shape. I'm holding the specimen upside down with the base of the colony (the pointed tip) at the top. The tip would have been attached to the substrate while the rest of the colony projected upward into the currents. I'm not sure if the attachment point was stable or flexible as I can't see any evidence for either scenario.

Another small specimen in matrix with the curved base point present.

The Verulam formation is middle Ordovician in age (Katian/Mohawkian stage) and is found in southern Ontario, Canada.